In applicant's copending U.S. application Ser. No. 740,650 an adapter is provided on a railtruck which can be in turn coupled to a receiving portion of a leading trailer. While this design performs in a satisfactory manner, it has the disadvantage in being unidirectional. In addition, the manually operated screw jack utilized in the prior design to shift the coupled pin may not be suitable for use when the trail is under heavy tension or compression, due to steep grades or long train consists.